The invention relates to a method of providing a pattern of apertures and/or cavities in a surface of a substrate, using a mechanical treatment.
Such a pattern is usually provided by means of powder blasting, grinding, lapping, sawing, drilling or another mechanical treatment.
If this method is used to provide cavities (ducts) in the (generally glass) channel plate of a PALC display (as known, for example, from WO 96/29689-A1, U.S. Pat. No. 5,626,772), the problem occurs that the treated part of the surface (the inner side of the channels) is microscopically rough after performing the mechanical treatment, so that the generated image does not have a sufficiently satisfactory contrast when the display incorporating the plate is being used.